Download Ch 15 Gudied Reading

Name: ________________________________________________
AP Biology
Mr. Croft
Chapter 15 Active Reading Guide
Regulation of Gene Expression
The overview for Chapter 15 introduces the idea that while all cells of an organism have
all genes in the genome, not all genes are expressed in every cell. What regulates
gene expression? Gene expression in prokaryotic cells differs from that in eukaryotic
cells. How do disruptions in gene regulation lead to cancer? This chapter gives you a
look at how genes are expressed and modulated.
Section 1
1. All genes are not “on” all the time. Using the metabolic needs of E. coli, explain why
not.
2. What are the two main ways of controlling metabolism in bacterial cells?
3. Feedback inhibition is a recurring mechanism throughout biological systems. In the
case of E. coli regulating tryptophan synthesis, is it positive or negative inhibition?
Explain your choice.
4. What is a promoter?
5. What is the operator? What does it do?
6. What is an operon?
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Adapted from Campbell Biology (9 Edition) – © 2011 Pearson Education, Inc.
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7. List the three components of an operon, and explain the role of each one.
8. How does a repressor protein work?
9. What are regulatory genes?
10. Distinguish between inducible and repressible operons, and describe one example
of each type.
11. Draw a sketch of the lac operon with the following terms: operon genes, operon,
RNA polymerase, mRNA, repressor protein, operator, repressor, regulatory gene,
inducer. Know the function of each structure.
12. Compare and contrast the lac operon and the trp operon.
13. What happens when a repressor is bound to the operator?
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Adapted from Campbell Biology (9 Edition) – © 2011 Pearson Education, Inc.
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14. What is CAP? How does CAP work?
15. Explain why CAP binding and stimulation of gene expression is positive regulation.
16. Describe the relationship between glucose supply, cAMP, and CAP.
17. How can both repressible and inducible operons be negative regulators?
Section 2
18. Even though all cells of an organism have the same genes, there is differential gene
expression. What does this mean?
19. What percentage of the genes of a typical human cell is expressed at any given
time?
20. What is the common control point of gene expression for all organisms?
21. Gene expression can be regulated by modifications of the chromatin. Distinguish
between heterochromatin and euchromatin as to their structure and activity.
22. What occurs in histone acetylation? How does it affect gene expression?
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Adapted from Campbell Biology (9 Edition) – © 2011 Pearson Education, Inc.
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23. What is DNA methylation? What role may it play in gene expression?
24. The inactive mammalian X chromosome is heavily methylated. What is the result of
this methylation?
25. What is genomic imprinting, and how is it maintained? Give an example discussed
earlier in human genetics.
26. Explain what is meant by epigenetic inheritance, and give an example of epigenetic
changes discussed in the text or in class.
27. Explain how enhancers and activators interact with transcription factors to affect
gene expression.
28. In prokaryotes, functionally related genes are usually clustered in a single operon.
What has been found to be the case in eukaryotes?
29. Operons have not been found in eukaryotic cells, and the genes coding for the
enzymes of a particular metabolic pathway are often scattered over different
chromosomes. What is a plausible mechanism for the coordination of gene
expression?
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Adapted from Campbell Biology (9 Edition) – © 2011 Pearson Education, Inc.
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30. How can alternative RNA splicing result in different proteins derived from the same
initial RNA transcript?
31. Posttranscriptional control includes regulation of mRNA degradation. Explain how
this affects translation.
32. How can proteins be activated, processed, and degraded? Give an example or
describe each process.
Section 3
33. It is now known that much of the RNA that is transcribed is not translated into
protein. These RNAs are called noncoding RNAs. Read carefully to discern a
crucial role played by these RNAs. What is this role?
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Adapted from Campbell Biology (9 Edition) – © 2011 Pearson Education, Inc.
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